“Downeast” is an indie thriller so simple as to be elemental.

It’s about a small town under the thumb of a local gangster, a crime long-ago covered-up and heroin headed for Boston’s rough and ever-so-Italian “North End.” The setting, the frosty lobster port of Long Island, Maine, just gives it a lived-in feel.

The Long Island depicted in the movie is a place “the young people” flee, so that there’s nothing left but lobstermen and the waterfront bars where they drink the chill off.

The first man we meet is the guy who “runs” this place. “Every town is built on bad decisions,” Kerrigan (Judson Mills, a “Walker, Texas Ranger” survivor) narrates. “And I built this town, brick by brick.”

He sees himself as being the lifeblood on Long Island, bringing in money, controlling not only the street trade but the trans-shipment of drugs down to Boston.

Tommy (Greg Finley) might’ve been a contender, once upon a time. He doesn’t box anymore. He works his dad’s boat, the Wild Irish Rose. And he pours the old drunk (Gareth Williams) into his pickup after every night’s beer-and-many-many “bumps.”

His old crush, Emma (Dylan Silver) is back in town. But their history isn’t a happy one. He’s just one of many locals who “didn’t talk” when her brother died, years before. And now, as he’s finding wrapped packages of drugs in his father’s lobster traps and facing new questions from Emma about what happened to Mikey, past and present are about to hit him all at once.

Finley, of “Blackjack: The Jackie Ryan Story,” came up with the story for “Downeast.” He plays a character pressed from all sides, the guy who hears or overhears every pithy line various bad guys mutter.

“Sometimes a man’s gotta do what he doesn’t want to do.”

Mills has the chewiest part, with writer-director Joe Raffa (“Dark Harbor”) stashing him away for use in scenes where he has the most impact, unloading almost every quotable line on Kerrigan.

“You can shear a sheep many times, you can only skin it once,” he counsels his minions, who need to keep their supplies of drugs and anxious customers alive to keep consuming them.

The biggest problem with being the big fish in this very small pond? “There’s always a bigger fish” in the bigger pond nearby.

The story clips along, never feeling rushed, never letting its over-familiar elements overwhelm its chief virtue, that setting described in the title — Downeast.

The resolution is entirely too pat, the romantic complications more detailed than you’d expect or that seems absolutely necessary. But if you like your thrillers compact and geographically distinct, “Downeast” delivers the goods.

MPA Rating: unrated, graphic violence, drug content, profanity.

Cast: Greg Finley, Dylan Silver, Judson Mills, Gareth Williams, Joss Glennie-Smith, Joe Holt and Kirk Fox

Credits: Scripted and directed by Joe Raffa. An APS release.

Running time: 1:29